by Jim Michaels and Doug Stanglin, USA TODAY

by Jim Michaels and Doug Stanglin, USA TODAY

A Marine shot and killed two fellow Marines at a barracks near Washington, D.C., late Thursday and early Friday then took his own life, according to the commander of Marine Corps Base Quantico.

All three, including a male and a female victim, were active duty Marines assigned to the Officer Candidate School, according to Col. David Maxwell, the base commander.

"This is truly a tragic loss again for the Marine Corps, which has had a number of tragic losses in the last couple of weeks," he said.

The shooting came four days after seven Marines were killed when a mortar exploded during a training exercise Monday night at a training facility and Army munitions depot in Nevada.

Maxwell said local authorities and military police, responding around 10:30 p.m. to reports of a gunshot, found a male Marine dead at Taylor Hall, a dorm-like section of the school.

They later found a second victim dead, along with the body of the suspected shooter, who died of a self-inflicted gunshot wound.

Maxwell denied initial reports that the suspected gunman had barricaded himself inside the barracks in a standoff. "This was not a standoff," he said.

Their identities were being withheld until after next of kin were notified. The investigation of the shooting is being conducted by the Naval Criminal Investigative Service.

The OCS is where Marines go to earn commission as second lieutenants.

The base, which is about 37 miles south of Washington, is also home to the FBI's training academy.

Defense Secretary Chuck Hagel "was saddened to learn of the shootings at Marine Corps Base Quantico," Pentagon spokesman George Little said in a statement. "This tragedy, as well as the tragedy in Nevada earlier this week, took the lives of Marines who volunteered to serve their nation. His heart and his prayers are with them and their families. He believes that the legendary strength of the United States Marine Corps will ensure that they are forever remembered."